I think I found a potential bug when using a bean to set a property if a message is coming through http. I wanted to check here before opening a bug in case I am missing something. It is very similar to the following bug which has already been fixed: https://stackoverflow.com/questions/40293128/camel-rest-service-throws-exception-when-returning-null/40317432#40317432.
The difference is that instead of returning null, an exception is thrown from the bean method. When that happen, I see the same behavior as described in the stackoverflow post above. I included an example on how to reproduce at the end of this email. Here is what I think happens:
Problem starts in BeanExpression:
1. The exchange is copied, BeanExpression: line 194: Exchange resultExchange = ExchangeHelper.createCopy(exchange, true)
2. The out body is then retrieved from the exchange, BeanExpression: line 201: result = resultExchange.getOut().getBody();
3. Since out() is null, the in() message is copied to the out(), this makes a copy of the HttpMessage, which is copied along with the original ServletRequest (which contains a closed stream) DefaultExchange.class line 317.
4. To copy the message from in to out, the method newInstance() from HttpMessage class is called. HttpMessage line 85
5. At this point, the new instance of HttpMessage tries to read the stream from the original message which is already closed, IOException.
Example just below, I would be expecting the EXCEPTION_CAUGHT to be the RuntimeException I throw but instead it's a RuntimeBeanExpressionException effectively wrapping a IOException.
I will try to provide an actual unit test shortly.